Filling and packaging systems are used to continuously produce packages having contents such as a liquid and a viscous object held in film. A typical filling and packaging system has a film supply apparatus which supplies a continuous sheet of film, a content supply apparatus which supplies contents, and a filling and packaging machine which fills the contents supplied from the content supply apparatus into the film as the machine shapes the film supplied from the film supply apparatus into a bag.
Specifically, in an aseptic packaging system, a film sterilizing apparatus is placed between a film supply apparatus and a filling and packaging machine, and a sterilizing apparatus is also provided for a content supply apparatus. In the film sterilizing apparatus, a hydrogen peroxide solution is often used as a sterilization liquid. Film unwound from the film supply apparatus is immersed in the sterilization liquid, the sterilization liquid is dried, and then the film is supplied to the filling and packaging machine.
A roll of film is set in the film supply apparatus, and the set film is unwound and supplied to the packaging machine. After the set film is used up, it is switched to a next film. To avoid an interruption of the operation of the packaging machine during the switching, a conventional film supply apparatus is configured such that the next film is stood by, and when the film on the use side nears a trailing end, the trailing end portion of the film on the use side is bonded to a leading end portion of the film stood by.
For example, each of Japanese Patent Laid-Open No. 2005-272125 (Patent Document 1) and Japanese Patent Laid-Open No. 2005-280927 (Patent Document 2) has disclosed a film supply apparatus which has two film holders each rotatably holding a roll of film, a film holding mechanism which holds a leading edge portion of the film on a stand-by side, and a seal mechanism which heat-seals the film on a use side and the film on the stand-by side throughout the width thereof. The film holding mechanism holds the film on the stand-by side by clamping a leading end portion thereof such that the film on the stand-by side is drawn out to face the film on the use side on a feeding path of the film on the use side. The seal mechanism is placed upstream of the held portion of the film on the stand-by side in a feeding direction of the film.
When the trailing end of the film on the use side is fed to a predetermined position corresponding to the position of the seal mechanism, the feeding of the film is stopped and the seal mechanism is driven. The driving of the seal mechanism causes the film on the use side and the film on the stand-by side to be heat-sealed, and at the same time, the leading end portion of the film on the stand-by side is released from the clamping by the film holding mechanism. Then, the feeding of the film is restarted, and the film originally placed on the stand-by side is supplied to the packaging machine as the film on the use side at this point in time. A film accumulation mechanism can be placed between the film supply apparatus and the packaging machine to realize the bonding of the films without stopping the operation of the packaging machine.
In the abovementioned conventional film supply apparatus, the film on the stand-by side is bonded to the film on the use side while the leading end portion of the former film remains clamped. Thus, as shown in FIG. 7 which is a section view of the bonded portions of the films, clamped leading end portion 100a of film 100 on the stand-by side is a non-fused portion which simply overlies film 101 on the use side. As a result, gap 102 is produced between leading end portion 100a of film 100 on the stand-by side and film 101 on the use side.
In trailing end portion 101a of film 101 on the use side, gap 103 may also be produced between films 100 and 101. Gap 103, however, can be prevented by appropriately controlling the feeding length of film 101 on the use side. On the other hand, the gap at leading end portion 100a of film 100 on the stand-by side is inevitably present as long as films 100 and 101 are heat-sealed while leading end portion 100a remains clamped.
When a packaging bag is produced with gap 102 present in this manner, gap 102 may be placed inside or outside the packaging bag depending on the relationship of the positions between films 100 and 101. If gap 102 is placed inside the packaging bag, the contents may fall into gap 102. If gap 102 is placed outside the packaging bag, a foreign matter may fall into gap 102.
If the conventional film supply apparatus is used in the aseptic packaging system, the sterilization liquid enters gap 102 when the bonded portion of films is immersed in the sterilization liquid. The sterilization liquid which entered gap 102 may stay there even after a dry step. Thus, if gap 102 is placed inside the packaging bag, the sterilization liquid staying in gap 102 may be incorporated into the packaging bag. If gap 102 is present outside the packaging bag, the sterilization liquid may drop in a film transfer process to adhere to another portion of the film. Especially when the sterilization liquid drops to a part which corresponds to the inner surface of the packaging bag, the sterilization liquid enters the packaging bag as a result.